1. Field of the Invention
The present invention relates to an improved spark plug in what is generally referred to as a pin-to-pin configuration having greatly improved wear characteristics.
2. Description of the Related Art
Spark plugs of various designs are generally known from the related art. In the case of known spark plugs having what is generally referred to as a top electrode, where the ground electrode is disposed over the center electrode in the axial direction of the spark plug, pins that usually contain noble metal are used to improve the service life of the spark plug. These noble metal pins exhibit excellent resistance to corrosion and erosion. In addition, the mutually opposing configuration of the noble metal pins on the center electrode and on the ground electrode ensures a very effective ignition of the fuel mixture. The noble metal pins can be joined to the particular base electrodes by welding, for example. The noble metal pins are normally cylindrical and configured in a way that allows a pin of a larger of the two diameters to be mounted on the ground electrode, and a pin of the smaller of the pin diameters to be mounted on the center electrode. This measure provides a reliable overlap between the noble metal pin of the center electrode and that of the ground electrode, making it possible for even manufacturing-induced, as well as for tolerance-induced tolerances to be compensated for. Alternatively, the diameters of the noble metal pins are of the same size. In addition, single-spark ignition coils are typically used in modern internal combustion engines, where the center electrode is provided as a cathode. It turns out in this connection that the center electrode is subject to greater wear than is the ground electrode, the wear ratio being from 1/3 to 2/3. However, since the noble metal pins are very expensive components of the spark plugs, it would be desirable to have electrodes that exhibit a most uniform possible wear over the total service life of the spark plug.